Addressing Disparities in Outcomes of Screening for Colorectal Cancer in Community-Based Settings

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PROJECT SUMMARY/ABSTRACT: Colorectal cancer (CRC) is the second leading cause of cancer deaths in the United States and although the overall CRC mortality rate has been decreasing, disparities have persisted, particularly for Black and Native American people. CRC screening is highly effective and there is a welcome national attention on improving access to screening for groups that are socially disadvantaged. However, the benefits of screening depend on receiving both high-quality testing and timely follow-up care when abnormal. Thus, disparities may persist even when rates of participation in screening are similar across populations. Recently, the US Preventive Services Task Force highlighted a gap in the understanding of CRC disparities and the relative lack of interventions that have been shown to eliminate disparities by race and ethnicity. The goal of this application is to inform feasible and effective strategies for advancing health equity by elucidating the extent to which differences in care along the entire screening process cumulatively contribute to disparities. We will comprehensively evaluate the entire screening continuum from the tests used and screening quality to receipt of follow-up care and guideline-concordant treatment in a cohort of about 3.8 million people per year over a nearly 2-decade period in Kaiser Permanente Northern California (KPNC) and Kaiser Permanente Southern California (KPSC). We will use a mixed methods approach informed by health equity frameworks to examine: 1) the receipt and quality of screening for CRC, including follow-up when abnormal; 2) post-screening treatment and disease outcomes, including interval CRCs, 5-year survival, and age-standardized incidence and mortality, overall and by location; 3) the reasons for variations in quality and timely follow-up using qualitative interviews; and 4) the relative contributions of differences along the screening continuum to disparities in mortality by using microsimulation modeling. We will conduct our studies in a dynamic cohort of 45-85-year-old men and women in KPNC/KPSC during the 2003-2019 period. The members of KPNC and KPSC mirror the characteristics, in terms of social factors, of people in the regions served across California. The complete capture of all screening steps and diverse, well-defined populations enable studies of strategies across the screening continuum among social groups. Our analyses will compare the racial and ethnic groups and stratifications by race for each outcome over a nearly 2-decade period. We will interview patient-clinician dyads to elucidate reasons for variations in quality, follow-up, and outcome. We will also use the MISCAN-Colon microsimulation model to examine the extent to which disparities in mortality are attributable to differences found across each step in the screening continuum. The proposed research has a high potential to inform the prioritization of strategies for advancing health equity across disadvantaged racial and ethnic minority groups and thus advance a national public health priority. The 1½ decades of high-impact collaboration in our team, and the setting and rigor of our application support the feasibility and high potential for impact in the field.